ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Structure of vanadium(III) hydroxo complexes

L. Pajdowski

Department of Inorganic Chemistry, University of Wroclaw, Poland

Abstract: The absorption spectrum of vanadium(III) slightly acid solutions (pH > 2) exhibits a strong band with maximum at 436 nm, which so far was ascribed to the VOH²⁺ ion. The average molar absorptivity considerably increases with the increase of metal concentration as well as with the increase of p H up to the value pH 3.2—3.5. At higher pH the absorbance decreases. Our studies show that the visible absorption spectrum of vanadium(III) in the range pH 2— 3.5 is a charge-transfer spectrum of the binuclear hydroxo complex. The weak bands of the VOH²⁺ ion are isolated out of the spectrum graphically and by calculations. Vanishing absorption in 436 nm band at higher values of pH and normal magnetic behaviour of the binuclear complex may be explained as due to a change of strongly absorbing binuclear complex into a new polynuclear (D_4h) complex with higher ratio of OH groups per vanadium atom.

Full paper in Portable Document Format: 193a192.pdf

Chemical Papers 19 (3) 192–199 (1965)